Resistance mounting structure



May 16, 1961 R. E; DU Bols RESISTANCE MOUNTING STRUCTURE Filed May l5, 1959 E 2 l 5 i HMM l l 1 l l l I I r l I l MHH- I B m E /I /l ...DI n.7-

HUM|F|H d HTW h a h wn INVENTOR ROBERT E. DUBOIS BY 7M, EN f ATTORNEY RESISTANCE MOUNTING STRUCTURE Robert E. Du Bois, 7541 Woodmoor Ave., Hammond, Ind.

Filed May 13, 1959, Ser. No. 812,945

7 Claims. (Cl. 338-283) This invention relates generally to electrical resistance structures and more specifically to the mounting structure for a zigezag resistance unit.

Resistor grids, such as those used as heat dissipating units, expand and contract in service due to heating and cooling, and unless compensating means is provided in the mounting of such grids in a supporting frame, an unnecessary strain is set up in the grids causing warping, breakage and possible short circuiting. The prior art has generally provided for this expansion and contraction by the use of spring elements or by a loose mounting of the grid within a frame. Neither solution is effective in economically and firmly supporting a grid within a mounting frame with no loose joints, while still permitting the inherent expansion and contraction of the grids in service.

It is therefore the primary object of this invention to provide an improved mount for a resistor grid unit which is effective in firmly supporting a resistor grid within a mounting frame while permitting relatively unrestricted expansion and contraction of the grid under service conditions.

A more specific object of this invention is to provide a mount for a resistor grid unit which is effective in firmly supporting a resistor grid Within a mounting frame wherein the support is obtained with a minimum of contact between the mount and the grid, and wherein the grid is permitted relatively unrestricted expansion and contraction under service conditions.

Another object of this invention is to provide a mounting structure forresistor grid units in a standard frame whereby grid units of varying sizes, quantities and arrangements may be readily mounted in the frame without alteration ofthe basic framing structure.

A further object of this invention is to provide a mounting structure for resistor Igrid units wherein a standard frame is rendered adaptable to the reception of plural grid units in assorted arrangements to permit effective resistor cooling under service conditions.

Another object of this invention is to provide an improved mount for a resistor grid unit in a supporting frame which includes an inexpensive, rigid bracket which will effectively retain the grids within the frame while permitting inherent expansion and contraction of the grids under normal service conditions.

With the foregoing and other objects in View, the invention resides in the following specification and appended claims, certain embodiments and details of construction of which are illustrated in the accompanying drawings in which:

Figure l is a fragmentary View in front elevation of the resistor structure embodying this invention;

Figure 2 is a fragmentary sectioned view of the invention taken along the lines 2-2 in Figure 1;

Figure 3 is a fragmentary, partially sectioned view similar to Figure 2 but illustrating a modified form of this invention; and

Figure 4 is a perspective view of the grid mounting bracket of this invention. l .Y

United States Patent i vPatented May 16, 1961 ICC Referring more particularly to the drawings, a resistor frame generally indicated at 10 is illustrated as including substantially U-shaped end frame members 11 and 12 and top and bottom frame members 13 and 14. The members 13 and 14 are preferably solid, rigid pieces of insulating material of considerable resistance to bending, cracking or other possible inherent defects. The members 13 and 14 are provided with spaced longitudinally bored or molded passageways to receive mounting bolts 15 which are utilized to secure the various frame members together into a rigid structure.

In the form of the invention illustrated in Figures l and 2, the members 13 and 14 are provided with a plurality of regularly spaced openings 16. The openings 16 are preferably each of the same dimension and contour and may extend completely through the members 13 and 14 as illustrated or only partially therethrough as a particular structure might require. The holes 16 act as mounting recesses for grid supporting brackets 17, as illustrated in Figure 4. Each bracket 17 includes a central bridging member 18 and a plurality of straight, oppositely directed legs 19 intermediate the ends of the member 18. At the ends of member 18 are legs 20 and 21 having their upper portions 22 and 23, respectively, bent over transversely of the longitudinal dimension of the bracket 17 for a purpose to be described. As will be readily obvious from the drawings, the bridging member is angularly and alternately reversely directed over its length between adjacent legs 19. The adjacent legs of the bracket such as 24 and 2S, are therefore offset to either side of a central plane through the bracket 17 for a purpose to be described. The spacing, contour and dimensions of the depending portions of the legs, as viewed in Figure 4, are such as to exactly correspond to the similar physical features of the holes 16 in members 13 and 14. As a matter of fact, the depending portions of legs 19 should fit in the holes 16 in a preferably light friction fit relationship.

As illustrated in Figures l and 2, a plurality of brackets 17 are positioned or mounted along the facing surfaces of mounting insulating members 13 and 14. The depending portions of bracket legs 19 enter into corresponding or matching holes 16, and the bracket bridging members 18 effectively engage or rest on the inner surfaces of the members 13 and 14.

A zigzag resistor grid 26 of a generally heavy, rigid, flat form includes a plurality of integral portions folded upon themselves to form a series of upper and lower peaks 27 and 28 as viewed in Figure l. Each peak is positioned Within the confines of legs 19 of a bracket 17. As thus supported, the legs 19, which frictionally engage the grid peak areas, confine the grid 26 against bodily movement relative to longitudinal dimension of the frame 1l). The peaks 28 of grid 26 rest on the relatively narrow surfaces of bridging member 18 between each adjoining pair of legs 19. Thus in a supported position in a bracket 17, a peak 28 will be in limited area contact with the bridging member 18 to reduce the effective heat transfer from the grid to the bracket and the frame 10. Likewise, the limited contact area described, reduces the chances of hot spots being created in the grid, as air or air under pressure is circulated through the structure to aid in the cooling or heat dissipation. The air is simply able to contact most of the lower edge of peak 28 to remove heat therefrom. The legs 19 being offset to either side of a central plane through the bracket only, provide for friction contact with the peak 28 of the grid 26 on only one side or face of the grid at a time. Thus air circulating adjacent the opposite side of the grid 26 from the contact area with a leg 19 will draw olf heat quickly enough to avoid hot spots. As illustrated in Figure 1, the peaks 27 do no contact the bridging members 18 of 'the upper brackets 17. The grid 26 is dimensioned between adjacent peaks so that the distance between the bridging members 1Sof the upper and lower brackets is "greater than the length of any individual reverse fold of the -grid between peaks 527 and 28.

Thus as seen 1in Figure 1, the legs -19 coniine the peaks 27 to arxed Vposition relative to the frame and permit expansion and Ycontraction of the reverse folds of the grid between lopposed or'facing brackets on the members 13 and 14. The bent-over portions 22 and 23 of'bracket legs 20 and 21 prevent Iany substantial transverse movement of a grid peak 27 or 2S relative to the frame 10. Thus it is seen that the brackets 17 eifectively and firmly support the grid 26 within the frame 10 while permitting inherent expansion and contraction of the grid folds under varying temperature conditions during service.

In Figure 3 the adaptability of the basic concepts of the invention is illustrated in a somewhat modified form. An insulating member 29 similar to a member 13 or 14 is provided with holes 30 and 31, the said holes being regularly and alternately olfset from one row to the next. Brackets 32, 33, and 34 are positioned on the member 29 in such a manner as to be oifset from each other in adjacent rows. Thus assume that it is required to provide a resistor structure including a pair of zig-zag resistor grids instead of the single grid of Figures l and 2. By using a series of brackets 32 and 34 along the longitudinal dimension of the member 29, then two zig-zag grids could be mounted on the brackets, that is one each on brackets 32 and 34. By offsetting the brackets as shown then the folds of the resistors in the two grids will also be relatively offset to render the grids more suitable or adaptable to air cooling. The bracket 33 is illustrative of a positioning of an adjacent bracket 33 to a bracket 32 where the former is placed inwardly of the `frame 10 relative to the latter. This arrangement would not be suitable for a single zig-zag resistor but is adaptable to offsetting the mounting of over-all relatively short length grids for spacing or cooling purposes, The arrangement of bracket 33 relative to bracket 34 also offers a variation of the basic spacing between brackets 32 and 34.

Thus, it is seen that the form of Figure 3 is most admirably suited to the mounting of a plurality of rows of zig-zag resistors with the mounting of supporting brackets being selective, if desired, to place the reverse folds of adjacent portions of the grids of ythe plural rows of grids in alternate, oifset relationship to each other longitudinally of the member 29.

It should be obvious to one skilled in the art that the invention provides an economical and effective structure to firmly secure a resistor grid in a frame while permitting `free expansion and contraction under varying temperature conditions. The structure may be readily adaptable to design Variations particularly with regard to the sizes or spacing of the holes 1f, 30, and 31 and to the physical counterparts in the legs 19 of brackets 17. These obvious points of variation are deemed to be well within the purview of this invention and within the scope of the appended claims.

I claim:

1. An electrical resistance structure comprisinga pair of end frame members, a pair of insulator frame members interconnected with the end members to form a rigid frame, said insulator frame members being provided with a plurality of spaced openings arranged in a' definite pattern, a plurality of grid mounting brackets, each of said brackets including a central bridging member and a plurality of longitudinally spaced legs alternately offset in 'a lateral direction connected with the bridging member and extending to either side thereof, with the bridging members being alternately, angularly directed between adjacent legs over the length of the bracket, the portions 'of the bracket legs extending to one vside of the bridging member entering the openings of the insulator frame member -to secure the brackets to the frame by -afriction tit, land aresistor grid, said grid being supported by the legs of the brackets not previously used in connecting the brackets to the frame, said support of the grid by the brackets constituting a sliding friction t between contacting surfaces to permit free expansion and contraction of the grid.

2. An electrical resistance structure comprising a frame, including a plurality of opposed frame members, a resistor grid carried by the frame, and a plurality of brackets to support and retain the grid on the frame, certain of said frame members including portions provided with openings arranged in a definite pattern, each of said brackets including a central bridging member and a plurality of longitudinally spaced legs -alternately offset in a lateral direction connected with the bridging member and extending to either side thereof, with the bridging members being alternately, angularly directed between adjacent legs over the length of the bracket, the portions of the bracket legs extending to one side of the bridging member entering the openings of the frame members to secure the brackets to the frame by a friction tit, said grid being supported by the legs of the brackets not previously used in connecting the brackets to the frame, said support of the grid by the legs of the brackets constituting a sliding friction tit between contacting surfaces to permit free expansion and contraction of the grid.

3. A mounting structure for electrical resistor grids comprising a plurality of frame members, two of said frame members being in spaced, opposed relationship and being provided with a plurality of openings arranged ina definite similar pattern on each member, a plurality of brackets, each said bracket including a central bridging member and a plurality of spaced legs integral with the bridging member and extending to either side thereof with the bridging member being alternately, angularly directed between adjacent legs over the length of the bracket to thus place the legs in an offset position relative to a central plane through the bracket, the legs of the bracket on one side of the bridging member being so designed as to enter the openings of the frame members and retain the bracket on the frame member by a friction tit, and the legs on the opposite side of the bridging member receiving and supporting portions of a grid in a free sliding relationship to permit expansion and contraction of the grid under varying temperature conditions.

4. The invention according to claim 3 wherein the terminal leg at either end of each bracket is partially deformed toward the central plane through the bracket to provide integral abutments to preclude any substantial movement of the grid lengthwise of the bracket.

5. A mounting structure for electrical resistor grids comprising a plurality of frame members, two of said frame members being in spaced opposed relationship and being provided with a plurality of openings arranged in a denite similar patter on each member, a plurality of brackets, each said bracket including a central bridging member and a plurality of spaced legs integral with the bridging member and extending to either side thereof with the bridging member being alternately, angularly directed between adjacent legs over the length of the bracket to thus place the legs in an offset position relative to a central plane through the bracket, the legs of the bracket on one side of the bridging member being so designed as to enter the openings of the frame members and retain the bracket on the frame member by a friction tit, and the legs on the opposite side of the bridgingmember receiving and supporting portions of a grid in free sliding relationship, the distance between the bridging members of corresponding brackets mounted on the opposed frame members being greater than the longitudinal dimension of the portion of the grid to be supported by said corresponding brackets so that expansion and contraction of the grid under varying temperature conditions may occur.

6. The invention according to claim 5 wherein the terminal leg at either end of each bracket is partially deformed toward the central plane through the bracket to provide integral abutments to preclude any substantial movement of the grid lengthwise of the bracket.

7. An electrical resistance structure comprising a pair of end frame members, a pair of opposed, spaced insulator frame members interconnected with the end members to form a rigid frame, each said insulator frame member being provided with a plurality of rows of aligned openings extending longitudinally of each said insulator member, each row of openings being offset from adjoining rows in the longitudinal direction in such a manner as to form a plurality of transverse rows of aligned openings in each insulator frame member, a plurality of grid mounting brackets supported on the facing surfaces of the insulator frame members, each said bracket being provided with a plurality of spaced supporting legs over its length with adjacent legs being offset alternately and laterally of a, plane through the bracket, the longitudinal and llateral spacing of the bracket legs being predesigned to agree with the offset spacing of the rows of openings in each frame member, so that each such bracket may be selectively mounted by its legs on an insulator frame member, and a resistor grid carried by the brackets, the placement of the grids within the frame member being predetermined selectively by the prearranged positioning ofthe supporting brackets.

Weide Oct. 25, 1955 Kuhn et al Feb. 17, 1959 

